1. Field of the Invention
This invention relates to a microfilm and a printer adapted for use with a microfilm, and more particularly, to means for detecting and discriminating the sizes of microimages photographed on the microfilm.
In a microfilm, a large number of microimages are photographically formed on a reduced scale in proportion to corresponding A3, A4 size sheets, for example. Therefore, when the microimages are enlarged and copied from the microfilm by a reader/printer or a printer, it is necessary to supply correct sizes of copying sheets, such as A3, A4 and the like, corresponding to the sizes of the respective microimages.
2. Description of the Related Art
In a reader/printer or the like, when the microimages are read or copied, the size detection and discrimination of microimages has been conventionally conducted as follows.
An operator directly visually observes the microfilm or a screen on which the microimages are enlarged and projected, in order to discriminate the sizes of the microimages. However, such a detecting method is troublesome for the operator and sometimes causes errors in detection, and therefore, errors in selection of the copying sheets. Where such errors occur, the correct copying sheets are not supplied in the printer, so that if, for example, an A4 sheet was incorrectly supplied in place of an A3 sheet, a part of image would not be formed on the copying sheet, conversely, if the A3 sheet was incorrectly supplied in place of the A4 sheet, the image would be copied only on the central portion of the copying sheet and toner would be adhered to the peripheral portion thereof, which would increase the consumption of the toner.
Japanese Unexamined Patent Publication No. 50-53050 discloses a reader/printer for apertured cards, each card having an aperture containing information indicating the size of the microimage photographically formed on the card. Therefore, the size of microimage can be detected by reading out the aperture information. However, at least an exclusive detecting means is necessary for reading out such information. Therefore, in this reader/printer, the means for projecting images and the peripheral structural portions thereof must become complicated.
A detecting means, such as disclosed in Japanese Unexamined Patent Publication No. 59-30550, is also known, in which a plurality of detecting sensors are arranged so as to come into and out of the whole effective area of the optical path from the microimage of the microfilm and the size of the microimage is directly detected and discriminated in accordance with the signals from these sensors, so that a correct size of copying sheet corresponding to the size of the microimage is selectively supplied. However, this detecting system requires many sensors, which not only increases the total cost but also makes the process of discrimination complicated, and a special driving means is necessary for driving the plurality of sensors coming into and out of the optical path. Therefore, in continuous copying, it is difficult to increase the efficiency of operation.
In U.S. Pat. No. 3,744,890, a microfilm is provided with marks at the peripheries of the microimages. However, these marks do not serve to indicate the sizes of the microimages, but are either frame detection marks or frame group (case) indication marks.